Device for wireless transmission of data and/or power

ABSTRACT

The present invention relates to a device ( 700   a,    700   b,    700   c ) for wireless transmission of data and/or power between the device and another device of a system, in particular of a patient monitoring system. To meet stringent relative time errors at low complexity the device comprises a connector ( 701 ) comprising a data transmission unit ( 703 ) and a magnetic coupling unit ( 702, 704 ) for transmitting power to and/or receiving power. A detection unit ( 705 ) detects coupling of a counterpart connector of another device of the system with the connector ( 701 ). A control unit ( 707 ) uses the detection that a counterpart connector of another device of the system has been coupled with the connector ( 701 ) as a trigger to determine and/or reset a relative time difference between a clock signal used by the device and a clock signal of the other device using i) the high frequency power signal of the magnetic coupling unit ( 702, 704 ) and of a magnetic coupling unit of the counterpart connector and/or ii) a received time calibration signal for determining and/or resetting the relative time difference.

FIELD OF THE INVENTION

The present invention relates to a device for wireless transmission ofdata and/or power between the device and another device of a system, inparticular of a patient monitoring system.

BACKGROUND OF THE INVENTION

Wireless charging or powering of devices in general is an establishedtechnique that is convenient to users. Wireless powering can also beused in harsh environments where corrosion or moisture might jeopardizefunctionality or safety when galvanic contacts are used. There areseveral standards for wireless power such as Qi, PMA, Rezense andWiPower, and the market is growing rapidly. These techniques are mostlyused for charging a battery powered device (e.g. a mobile phone, atablet computer, etc.). Charging of multiple devices is possible. Forinstance in the Qi standard power plates with many smaller coils areavailable, however the devices need to be precisely positioned adjacentto each other (in the horizontal plane).

High-end patient monitoring is expanding from its traditionalapplication in the critical care arena (ICU, OR) towards lower acuitysettings such as the general ward, hospital-to-home, connected primarycare, etc. The success of the existing high-end products is due to thequality of the measurements, their modularity, the overall systemconnectivity, the user interface and its consistency (backwardscompatibility) across the total product line. At the same time the valuesegment market is expanding rapidly to address emerging countries andlower acuity settings where low-cost is of prime concern. In thesemarkets compromises may be made on modularity, connectivity and(sometimes) measurement quality.

In the lifestyle and sports arena also physiological measurements areused more and more (such as heart rate, respiration rate, SpO2).

In said new application spaces wearable (cordless) sensors,miniaturization and low-power are necessary. The basic requirementsacross all these segments are the same, namely excellent measurementquality compared with non-compromised electrical patient safety. Thelatter is strictly regulated in the IEC 60601 standard and dictates in aworst case scenario (direct connection to the heart) a 10 μA maximumleakage current, 4 kV isolation towards ground and 1.5 kV isolationbetween each of the measurements. Additionally, the patient monitor mustbe able to withstand high differential voltages introduced by adefibrillator and large RF voltages from a surgical knife.

Conventional isolation and protection concepts are based on inductivepower couplers (transformers) and optical data couplers for datatransport, next to maintaining sufficient creeping and clearance betweenPCBs and connector pins.

Synchronization of clocks in computer networks and sensor systems is awell-known problem and solutions are available for both centralized anddistributed systems. Synchronization of vital sign waveforms in patientmonitoring is a major challenge, where requirements are severe. It isimportant that for instance waves shown on the display correspond beatby beat. Moreover the delay from signal to signal (for instance ECG toInvasive Blood Pressure (IBP) is equally important as it may containimportant clinical information. Recently continuous non-invasive bloodpressure measurements have been proposed based on Pulse Arrival Time(PAT) or Pulse Transit Time (PTT). For these methods timing errorsbetween sensors must be smaller than 1 ms. Generally speaking,monitoring applications require sub millisecond timing accuracy.

Present solutions often use one master clock and multiple slave clocksin the devices connected via a cabled network. Messages are sent via thenetwork to synchronize clocks. It is not straightforward to apply suchtechniques in a wireless sensor system as is used in wearable patientmonitoring devices. Sometimes a master clock signal is transmitted buttiming accuracy is typically a few ms to 100's of ms depending on theradio standard. Although much better timing sync is in principlepossible for a radio (like Wi-Fi or Bluetooth (BT) micro second timestamps synchronization) such accuracy can only be reached with dedicatedlow-level implementation, not on top of a regular radio protocolimplementation. Furthermore, the modules generally each have a separatemodule clock with its own drift. This requires calibration at regularintervals.

Other methods rely on the emission of a common time stamp signal andthen derive timing signals locally in the devices based on their ownlocal crystal oscillator. However, many standard radio protocolimplementations do not allow synchronization at sub-millisecondaccuracy, and in practical wearable applications the radio link may notalways be available, while the medical application still requirescontinuous local signal synchronization.

Hence, there is a need for a solution that meets stringent relative timeerrors, for instance for a sensor system comprising dielectricallyisolated nodes with only one power source. Moreover, there is a need fora solution that requires only minimal increase in complexity to achievethe required specifications (i.e. drifts less than 1 ms) over a periodof several hours or days.

US 2007/0254726 A1 discloses an apparatus including a wirelesstransmitter modulating a carrier wave by transmission data andwirelessly communicating a signal, a wireless receiver mixing thewireless transmitter signal and a carrier wave and receiving thetransmission data, a power carrier wave clock generator provided on oneof the wireless transmitter and receiver generating a power carrier waveclock, a non-contact power transmitter transmitting power between thewireless transmitter and receiver through electromagnetic induction fromthe power carrier wave clock, a carrier wave generator mounted on theone of the wireless transmitter or receiver, and generating a carrierwave based on the power carrier wave clock, and a carrier wavereproducer mounted on the other of the wireless transmitter or receiver,and reproducing a carrier wave having the same frequency as the carrierwave based on a clock having the same frequency as the power carrierwave clock.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a device forwireless transmission of data and/or power that meets stringent relativetime errors at low complexity.

In a first aspect of the present invention a device for wirelesstransmission of data and/or power between the device and another deviceof a system, in particular of a patient monitoring system, is presented,said device comprising:

a connector comprising a data transmission unit arranged fortransmitting data to and/or receiving data from another device of thesystem having a counterpart connector, and a magnetic coupling unit fortransmitting power to and/or receiving power from another device of thesystem having a counterpart connector by use of inductive coupling usinga high frequency power signal,

a detection unit for detecting coupling of a counterpart connector ofanother device of the system with the connector, and

a control unit for using the detection that a counterpart connector ofanother device of the system has been coupled with the connector as atrigger to determine and/or reset a relative time difference between aclock signal used by the device and a clock signal of the other deviceusing i) the high frequency power signal of the magnetic coupling unitand of a magnetic coupling unit of the counterpart connector and/or ii)a received time calibration signal for determining and/or resetting therelative time difference.

Preferred embodiments of the invention are defined in the dependentclaims.

One element of the present invention includes the use of an automaticdetection when e.g. a sensor node is added to the system. This moment intime can be detected rather precisely, e.g. with sub-ms accuracy in allnodes providing a highly accurate (sub-ms) common time stamp in eachnode. Another element of the present invention is to exploit the commonhigh frequency signal (e.g. in the range of 100 kHz) to the nodes thatis used to transfer power to the different nodes. For nodes that are notin close proximity a dielectrically isolated cable may be used for thepower and wireless data transfer. Furthermore, a wireless message fromthe system master can be used for a time stamp for all nodes.

The present invention thus provides a solution that can meet stringentrelative time errors for a sensor system comprising dielectricallyisolated nodes with only one power source. Moreover, only minimalincrease in complexity is needed to achieve desired specifications (e.g.drifts less than 1 ms) over a period of several hours or days.

Further, embodiments of the present invention address at least some ofthe drawbacks of using wireless data communication, e.g. in a clinicalsetting. Particularly in systems using wireless devices it is of primeconcern to implement and maintain unambiguous coupling between thedevices. For instance, in a patient monitoring system using wirelessmeasurement modules, it is important to ensure a robust couplingmechanism for coupling of patient and devices, such as measurementmodules and the patient monitoring device. Such a coupling mechanism isgenerally known as “pairing” or “association” and is generally nottrivial to implement in crowded areas with many different kinds ofdevices, such as hospitals. Further, the transitions between caresettings (e.g. from OR to ICU or recovery) should be seamless andunambiguous, without any disturbance of the clinical workflow.Furthermore, patient re-location or mobile patients (in a ward or athome) are another challenge to solve.

In an embodiment the detection unit is configured to detect coupling ofa counterpart connector in a magnetic, electric or optical manner. Theway of detecting coupling is not essential, but can be chosen accordingto the circumstances and the application. These different ways ofdetection include NFC and Bluetooth as useful options. The detectionunit may be configured to detect coupling of a counterpart connector bydetecting if the strength of magnetic coupling (often referred to asmagnetic coupling factor k (0<=k<=1)) between the magnetic coupling unitand a magnetic coupling unit of the counterpart connector exceeds amagnetic coupling threshold, in particular by detecting impedance,resonance frequency and/or induced voltage for detecting the strength ofmagnetic coupling and/or by detecting if the intensity of data receivedby the data transmission unit from a data transmission unit of the otherdevice exceeds an intensity threshold, in particular by detecting signalintensity and/or antenna impedance of an antenna of the datatransmission unit for detecting the intensity of received data.

In case components are already connected, this is clear from theavailability of power and strong RF signal. Attachment of a newcomponent may be detected by use a polling mechanism to check theincrease of magnetic coupling (and, optionally, an RF signal used fordata transmission. Detection of disconnecting components may beperformed by the inverse process: a polling mechanism to measure adecrease of the strength of magnetic coupling by use e.g. of impedance,resonance frequency and/or induced voltage (and, optionally, of the RFsignal). Optionally, the RF signal strength may be measured in addition.

The device may further comprise a storage unit for storing the moment ofdetection that a counterpart connector of another device of the systemhas been coupled with the connector as a time stamp. The datatransmission unit may then be configured to transmit the time stampand/or a determined relative difference between the clock signal used bythe device and the clock signal of the other device to the other devicefor storage in a master device of the system.

In another embodiment the other device comprises a battery, wherein thehigh frequency power signal used for transmitting power from the batteryto the device is used for determining and/or resetting the relative timedifference. Further, the device may also comprise a battery, wherein thecontrol unit is configured to switch off the battery or generate acontrol signal for transmission to the other device for switching offthe battery of the other device.

The present invention further enables that one of the device acts as amaster not, i.e. the data transmission unit may be configured to receivea master clock signal from the other device or to transmit a masterclock signal to the other device.

The device may further comprise a galvanic connection unit for galvaniccoupling of the device to a third device having a counterpart galvanicconnection unit and for receiving a master clock signal from the thirddevice for calibrating the clock signal used by the device.

The device may further comprise a patient side connection unit forconnecting the device to one or more sensors to receive one or morephysiologic sensor signals, wherein the device is configured tocalibrate the clock signal used by the device based on a periodicity ofa received physiologic signal.

In various other embodiments the device may comprise a clock unit forgenerating the clock signal used by the device and/or a counter forcounting the number of pulses of the high frequency power signal,wherein the counted number is used for calibrating the clock signal usedby the device. The counter may hereby be configured to reset to zerowhen the device is coupled to or decoupled from another device or whenthe inductive coupling is interrupted or when an externalsynchronization event is detected.

The control unit may further be configured to decide if a received orgenerated high frequency power signal is transmitted to the other deviceor if a new high frequency power signal with different frequency and/orphase is regenerated. Also in this context the Qi standard may be used.

Still further, the data transmission unit may be configured fortransmitting data by use of RF transmission, optical transmission,capacitive coupling or near field communication. The technology used fordata transmission may e.g. be chosen according to the environment orapplication.

Preferably, RF transmission by use of an RF antenna is used. Hence, in apreferable embodiment the connector comprises a carrier, wherein saiddata transmission unit comprises an RF antenna arranged in or on thecarrier and an RF circuit for driving the RF antenna and/or obtaining RFsignals received by the RF antenna. The carrier may e.g. be a PCB.

Various designs of the RF antenna are generally possible. Preferredantenna designs include that the RF antenna is shaped in the form of astripe, ring, planar inverted F or planar folded dipole. Further, the RFantenna is preferably arranged rotational symmetrically, which avoidsthe need for a predetermined rotational positioning of the connectorwith respect to a counterpart connector when connecting them. In anexemplary implementation a quarter wavelength planar inverted F-antennamay be used.

The magnetic coupling unit preferably comprises a flux concentrator forconcentrating magnetic flux and one or more coils arranged around partof the flux concentrator. Thus, inductive coupling like in a transformeris preferably used for the transmission of power.

The flux concentrator may comprise a core shaped in the form of a C or Eand/or may be arranged rotational symmetrically, which also supportsavoiding the need for a predetermined rotational positioning of theconnector with respect to a counterpart connector when connecting them.

Various designs of the flux concentrator and various numbers, designsand positions of the coils and the RF antenna(s) are generally possibleaccording to the present invention, depending on the kind ofapplication, the size, the costs, etc.

According to another embodiment the device may further comprise a dataunit for generating and/or receiving data, and/or a power unit forsupplying and/or consuming power. This e.g. enables processing ofreceived data in the device itself.

The device according to the present invention may be coupled with acentral monitoring device or hub (which may also be regarded as a devicein the sense of the present invention) effectively forming a patientnetwork. Many network topologies are generally known and can generallybe used according to the present invention. Such topologies include forexample Pico-nets and scatter nets described in the Bluetooth standard,whether or not combined with localization tracking and master/slaveconfigurations.

Devices according to the present invention may include different classesof network components, in particular:

measurement modules, battery modules, cable units;

monitoring devices and hubs, connected to the hospital IT system, cloud,fog or DHP;

storage devices (e.g. a wireless stick as temporary ID storage medium;

wearable devices, such as a wristband or plaster worn by patients foridentification, e.g. at a specific location.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiment(s) described hereinafter. Inthe following drawings

FIG. 1 shows a schematic diagram of a known system including a pluralityof devices,

FIG. 2 shows a schematic diagram of a first embodiment of a systemincluding a plurality of devices,

FIG. 3 schematically shows a first embodiment of a connector for use inthe system,

FIG. 4 schematically shows a second embodiment of a connector for use inthe system,

FIG. 5 schematically shows a third embodiment of a connector for use inthe system,

FIG. 6 schematically shows a fourth embodiment of a connector for use inthe system,

FIG. 7 schematically shows a fifth embodiment of a connector for use inthe system,

FIG. 8 shows a schematic diagram of a second embodiment of a system,

FIG. 9 shows a schematic diagram of a third embodiment of a system,

FIGS. 10A and 10B schematically show a cross-sectional view and a topview respectively of sixth embodiment of a connector for use in thesystem,

FIG. 10C schematically shows a sixth embodiment of a connector for usein the system in the connected state, coupled to a counterpartconnector,

FIG. 11 schematically shows a seventh embodiment of a connector for usein the system,

FIGS. 12A and 12B schematically show a cross-sectional view and a topview respectively of an eighth embodiment of a connector for use in thesystem,

FIGS. 13A and 13B schematically show a cross-sectional view and a topview respectively of a ninth embodiment of a connector for use in thesystem,

FIGS. 14A and 14B schematically show a cross-sectional view and a topview respectively of a tenth embodiment of a connector for use in thesystem,

FIG. 15 schematically shows an eleventh embodiment of a connector foruse in the system,

FIG. 16 schematically shows the layout of a connector with automaticswitching between modes,

FIGS. 17A, 17B, 17C, and 17D schematically show a cross-sectional view,a top view, and first and second perspective views respectively of afirst embodiment of a stackable connector for use in the system,

FIGS. 18A, 18B, and 18C schematically show a cross-sectional view, andfirst and second perspective views respectively of a stack of twoconnectors according to the first embodiment,

FIG. 19 schematically shows a stack of three connectors according to thefirst embodiment,

FIGS. 20A, 20B, and 20C schematically show arrangements of severaldevices in the form of a daisy chain, each device including one or moreof the connectors according to the invention,

FIGS. 21A and 21B schematically show a cross-sectional view and a topview respectively of a second embodiment of a stackable connector foruse in the system,

FIGS. 22A and 22B schematically show a cross-sectional view and a topview respectively of a third embodiment of a stackable connector for usein the system,

FIGS. 23A, 23B, and 23C schematically show a cross-sectional view, a topview, and a simplified cross-sectional view respectively of a fourthembodiment of a stackable connector for use in the system,

FIG. 24 schematically shows a fifth embodiment of a stackable connectorfor use in the system,

FIGS. 25A and 25B schematically show a cross-sectional view and a topview respectively of a sixth embodiment of a stackable connector for usein the system,

FIGS. 26A and 26B schematically show a cross-sectional view and a topview respectively of an embodiment of a connector for use in the systemhaving a lateral geometry,

FIGS. 27A and 27B schematically show a cross-sectional view and a topview respectively of a daisy chain using connectors as shown in FIGS.26A and 26B,

FIGS. 28A and 28B schematically show a cross-sectional view and a topview respectively of a body worn sensor arrangement using connectors asshown in FIGS. 26A and 26B,

FIG. 29 schematically shows the coupling of different modules and unitsto a patient monitor using connectors as shown in FIGS. 26A and 26B,

FIG. 30 shows a schematic diagram of a fourth embodiment of a systemcomprising a battery module,

FIG. 31 shows a general layout of a cable unit,

FIG. 32 illustrates the use of a cable unit in a high acuity setting,

FIG. 33 illustrates the use of a cable unit in a lower acuity setting,

FIG. 34 shows a schematic diagram of a fifth embodiment of a systemcomprising a storage module,

FIG. 35 shows a schematic diagram of an embodiment of a battery module,

FIG. 36 shows a schematic diagram of an embodiment of a cable unit,

FIG. 37 shows a schematic diagram of another embodiment of a deviceapplying a paring approach,

FIGS. 38A and 38B show different views of a first embodiment of a deviceaccording to the present invention,

FIGS. 39A and 39B show different views of a second embodiment of adevice according to the present invention,

FIGS. 40A and 40B show different views of a third embodiment of a deviceaccording to the present invention,

FIG. 41 shows a schematic diagram of a first embodiment of a systemincluding different devices according to the present invention,

FIG. 42 shows a schematic diagram of a second embodiment of a systemincluding different devices according to the present invention,

FIG. 43 shows a schematic diagram of a third embodiment of a systemincluding different devices according to the present invention,

FIGS. 44A and 44B show different views of a fourth embodiment of adevice according to the present invention,

FIG. 45 shows a schematic diagram of a fourth embodiment of a systemincluding different devices according to the present invention, and

FIG. 46 shows a schematic diagram of a fifth embodiment of a systemincluding different devices according to the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a schematic diagram of a known system 1 including aplurality of devices 2, 3, 4, 5, which are configured to transmit powerand data between them. Conventionally, a modular approach is usedaccording to which measurement modules 3, 4 (representing one type ofdevices) are connected via expensive gold-plated mainboard connectors(i.e. via a galvanic connection) 8 to a central processing unit 2(representing another type of devices), e.g. a central processor on amainboard of a patient monitor. Further, an isolated measurement module5 on the main board (representing another type of device) may beconnected to the main processing unit 2 in the same way.

Some measurements may be implemented directly on the mainboard itself.

Measurements are e.g. isolated from each other by using optocouplers 6for data transmission and a transformer 7 for power transmission. Allmetal parts share the same (protected) earth connection; themeasurements themselves are isolated from earth. Each measurement module3, 4, 5 may be connected, generally via a cable, to one or more sensors(not shown), e.g. a pulse oximetry sensor, an accelerometer, ECGelectrodes, that are placed at the patient's body.

In such a system electrical isolation involves a large part (at least30%) of the measurement costs. Further, mainboard connectors areexpensive and mechanically complex and cleaning is a challenge. Loweringthe costs is a strong requirement in the value segment and lower acuitysettings. Modularity is a strong requirement in high-end markets, andsomewhat less in lower acuity and value segment markets. Wearable(cordless) sensors and low-power are important for lower acuity caresettings. Further, aligning measurement concepts across the productrange of a company lowers costs and maintains the same quality for allmarket segments.

Thus, there is a strong need for a low-cost, low-power, flexible andmodular architecture, which is universally applicable to all patientmonitoring settings or, more generally, to all systems comprising aplurality of (different and/or identical devices) in which power and/ordata need to be transmitted under some or all of the above constraints.

FIG. 2 shows a schematic diagram of a first embodiment of a system 10including a plurality of devices 20, 30, 40, 50. According to theembodiment the devices 30, 40, 50 (e.g. representing measurement modules30, 40, 50) are each connected in a wireless manner to the centralprocessing unit 20, e.g. a patient monitor. Measurement modules, forinstance in a patient monitoring system, are connected to the centralprocessing unit 20 by individual magnetically coupled power transfer andnear field contactless data transfer (whereby there may also be deviceswhich only provide means for either magnetically coupled power transferor near field contactless data transfer). This flexible architecturecomplies with the following applications of physiological measurements:measurement modules located on the main board (i.e. in the centralprocessing unit 10), modular ‘plug-in’ measurement modules, measurementmodules located in a mobile measurement server connected to the centralprocessing unit 10, and cordless measurement modules. Generally, suchmeasurement modules are galvanically insulated from each other.Measurement modules may also be combined in one single mechanicalenclosure, and they may be fully galvanically insulated via their owncoils.

Magnetic power coupling may e.g. be integrated in tracks of the(mainboard) PCB or implemented as magnetic coils in each of the twodistinct parts of a connector for connecting two devices.

Contactless data transfer between two devices is preferably achieved vianear-field communications means, e.g. Bluetooth 4.0 (low energy), Wi-Fi,ZigBee, NFC, capacitive (e.g. via the parasitic capacitance of themagnetic coupling) or optical, wherein radio transfer is the preferredoption. Preferably a (e.g. standardized) radio protocol is used to becompliant with all four applications mentioned, e.g. BLE, which isalready integrated in many Commercial-Of-The-Shelf (COTS) components.Basically, in case the radiation field is confined within a certainvolume (e.g. inside the housing of the monitor) any non-regulated radioprotocol can be used.

Generally, each device that shall be able to transmit data and power ina cordless manner comprises a housing, a magnetic coupling unit arrangedwithin the housing for transmitting power to and/or receiving power fromanother device of the system having a counterpart connector by use ofinductive coupling, and a data transmission unit arranged fortransmitting data to and/or receiving data from another device of thesystem having a counterpart connector, in particular by use of RFtransmission, optical transmission, capacitive coupling or near fieldcommunication.

The measurement modules 30, 40 each comprise a housing 31, 41, amagnetic coupling unit 32, 42 and a data transmission unit 33, 43.Further, each of them comprises a patient side connection unit (PSC) 34,44 for (generally in a galvanic manner) connecting the respectivemeasurement module 30, 40 to a sensor or electrode (not shown) in orderto receive data signals from the sensor or electrode and/or transmitcontrol signals to the sensor or electrode. Optionally, further meansfor analog processing and/or digital processing may be provided, and ameasurement module could contain a small energy buffer (e.g. a batteryor super-capacitor) to bridge the transition time between wired-wirelessscenarios as well as during battery replacement.

The isolated measurement module 50, i.e. a measurement module integratedon the main board of the patient monitoring device, comprises a housing51, a magnetic coupling unit 52 and a data transmission unit 53.Further, it comprises a patient side connection unit (PSC) 54 as well.

The central processing unit 20 comprises a housing 21, several magneticcoupling units 22, 22 a, 22 c and several data transmission units 23, 23a, 23 b, which may also be combined into a single data transmissionunit, wherein a magnetic coupling unit and a data coupling unit form aconnection module for connecting one (external) device to the centralprocessing unit 20. Further, it comprises a supply terminal 24comprising an isolation barrier for coupling the central processing unit20 to an external power supply 60. Furthermore, the central processingunit 20 generally contains all the hardware needed for power and voltagegeneration, control, input/output, display and central processing ofdata from measurements and alarm generation.

The ability to transmit data and power between two devices of the system10 is indicated through blocks 61, 62, 63. It should be noted that thesystem 10 may also comprises devices, which are not configured fortransmitting and receiving data and power, but which are configured toonly transmit data and/or power or which are configured to only receivedata and/or power.

A first embodiment of a connector 100, 110 for wireless transmission ofdata and/or power between separate devices comprising such a connectoris schematically shown in a top view in FIG. 3. These connectors 100(e.g. of a central processing unit) and 110 (e.g. of a measurementmodule) represent a low-cost solution and can be implemented on-board.The tracks of a PCB 102, 112 may be used as transformer windings (i.e.coils) 101 (e.g. representing a primary coil), 111 (e.g. representing asecondary coil), separated in the horizontal and/or the verticaldirection. Magnetic coupling may be enhanced by adding a fluxconcentrator 103, e.g. a ferromagnetic core having two legs (eachcarrying one of the coils 101, 111) and two yokes connecting the twolegs to form a ring (which need not necessarily circular, but may alsohave other shapes such as rectangular, elliptical, etc. RF antennas 104,114 are integrated on the PCBs 102, 112 as well. A gap 105 between theconnectors 100, 110 provides an isolation barrier. A mainboard processor106 may be provided in the central processing unit and a measurementunit 116 may be provided on the measurement module.

FIG. 4 schematically shows a cross-sectional view of a second embodimentof a connector 120, 130 for use in the system providing isolatedmeasurement on the mainboard of the central processing unit. The coils101, 111 are located on different surfaces of the respective PCB 102,112 and are magnetically coupled via a flux concentrator 103.

Obviously, many variations on this approach are feasible. FIG. 5schematically shows a cross-sectional view of a third embodiment of aconnector 140, 150 for use in the system. In this embodiment a thirdin-between layer 107 is provided, which is arranged within the PCB 102,in vertical direction, on a height level in between the coil 101 and thecoil 111. The third in-between layer 107 is connected to ground toreduce stray capacitive coupling between the coils 101, 111. Furtherlayers, such as another ground layer 108, may be added for EMC reasons,as shown in FIG. 6 depicting a fourth embodiment of a connector 160, 170for use in the system.

FIG. 7 schematically shows a cross-sectional view of a fifth embodimentof a connector 180, 190 for use in the system. In this embodiment themeasurement PCB 112 is located on top of the mainboard PCB 102 with aninsulation foil 109 in between and magnetically coupling via the fluxconcentrator 103.

In still another variation of one of the above described embodiments thesecondary coil may be integrated on the die or in the package of anASIC, which comprise the electronic circuitry of the measurement.

Preferably, the main microprocessor on the central processing unitcontrols or drives the primary coil of the transformer. The AC voltageof the secondary coil is rectified and stabilized to supply themeasurement module. This approach may make use of the Qi standard (orother standard) of wireless charging, and the arrangement andconstruction of the components can generally be made to fulfillrequirements of one or more of these standards (e.g. the coils should beclose to the surface). Alternative methods may, however, also be used,and e.g. the AC voltage may be passed to the measurement module.

For data communication the central processing unit may comprise a nearfield radio-stack, communicating with the isolated measurements via e.g.Bluetooth Low Energy, ZigBee or in any other suitable way. Everynon-standard protocol is allowed in case the radiation is limited to aconfined housing.

RF transmission may be achieved via separate antennas, via capacitivecoupling pads or even via the parasitic capacitance of the transformercoils. Said parasitic capacitance should be kept very small to becompliant with the IEC 60601-2-49 standard isolation requirements, butthis constraint is e.g. achievable with transmission in the UHF radioband of 2.4 GHz or beyond.

FIG. 8 shows a schematic diagram of a second embodiment of a system 11including a plurality of devices 20, 30, 40. In this embodiment the oneor more measurement modules 30, 40 are e.g. fitted in a measurement rack20′ and are coupled to the central processing unit 20 by magneticconnectors 25, 35 (for the module 30) and 26, 46 (for the module 40)comprising a primary coil 101 of the central processing unit 20 in closeproximity to a secondary coil 111 and RF antenna 114 of the modules 30,40. For data transmission an RF antenna 104 may be provided in thecentral processing unit 20 and a corresponding RF antenna 114 may beprovided in the measurement modules 30, 50 (e.g. an antenna used innear-field mode for bridging small distances, such as BT, ZigBee, NFC,etc.

Due to the absence of pins, cleaning is easy. Hence, these connectors25, 35, 26, 46 replace the expensive and cumbersome cleanable galvanicconnectors as conventionally used and as shown in FIG. 1. Further, PSCunits 34, 44 may be provided for connection to respective sensors, e.g.a temperature sensor or a SpO2 sensor.

The system may further comprise a user interface 70 coupled to thecentral processing unit 20, e.g. comprising one or more displays,buttons, switches, etc. Further, a mains power transformer 71 may beprovided for connection to a mains power supply 60.

Measurements may be located inside a detachable small box (not shown),also called measurement server, close to the patient, which is connectedto the patient monitor via a cable comprising connectors as disclosedherein or via a wireless link, so that it can be operated in a hybridmode (i.e. in wired or wireless way). Within such a measurement serverevery measurement's battery will be charged during normal use. Whenevera patient needs to be moved, the link to the patient monitor might belost for a certain amount of time; nevertheless the individualmeasurements will continue to measure, record and process all the vitalsigns. Hence, no important data regarding the patient's health status islost. Again, in the vicinity of a patient monitor, the data might besynchronized again with a central server.

By putting in an additional re-chargeable battery 37, 47 into themeasurement modules 30, 40, as shown in FIG. 9 showing anotherembodiment of a system 12, the autonomous operation of said measurementmodules is possible. When re-fitted into the measurement rack thebattery is charged via the magnetic coupling. Battery management is atthe measurement module and may (optionally, but not preferably) be madeaccording to the Qi standard for wireless charging.

Data transfer preferably complies with existing connectivity standards.For example when using the Bluetooth LE 4.0 radio, the patient monitorbecomes direct applicable for the Continua Health Alliance, which is anon-profit open industry organization of healthcare and technologycompanies joining together in collaboration to improve the quality ofpersonal healthcare. The Continua Health Alliance is dedicated toestablishing a system of interoperable personal connected healthsolutions with the knowledge that extending those solutions into thehome fosters independence empowers individuals and provides theopportunity for truly personalized health and wellness management. Theseaims are supported by the present invention.

FIGS. 10 to 15 show further embodiments of a connector.

FIG. 10 schematically shows a cross-sectional view (FIG. 10A) and a topview (FIG. 10B) of a sixth embodiment of a connector 200 for use in thesystem in an unconnected state. The connector 200 comprises a PCB 202,which comprises a quarter wavelength planar inverted F-antenna (PIFA)204 as part of the data transmission unit integrated in the tracks 290.The RF antenna 204 is formed by an RF signal line 205 and a ground plane206. The magnetic field is generated by coils 201 a, 201 b wrappedaround the C-shaped (also called U-shaped) flux concentrator 203 madefrom a material with high magnetic permeability for the frequencies ofinterest. Additional conducting sheet material may be added (as cover)to short the remaining stray field in the electronics by eddy currents.Additional cladding of the core 203 may help to shield the RF signal,which is a short-range radio field 209. When no other connector isattached (i.e. in the unconnected state), the RF antenna 204 operates inthe far-field mode, wherein its directivity is pointed to the outsideworld as indicated in FIG. 10A.

A power unit 207 is coupled to the coils 201 for power supply to thecoils 201 and/or power reception from the coils 201. An RF unit 208 iscoupled to the RF antenna 204 for data supply to the RF antenna 204and/or data reception from the RF antenna 204.

In the connected state, as illustrated in FIG. 10C showing the connector200 coupled to a counterpart connector 210, the poles of both C-shapedflux concentrators 203, 213 and the antennas 204, 214 are almostperfectly aligned, so that the RF and magnetic fields are optimallycoupled and shielded from the outside world.

Connecting induces two effects:

i) Firstly, the magnetic coupling increases dramatically, e.g. fromk=0.5 to k>0.95, which may be detected directly (e.g. via the inducedvoltage) or indirectly (e.g. using proximity detection). Via a pollingmechanism this effect is recognized by the magnetic powering electronics(e.g. Qi, PowerMat or custom) via the changed coil impedance, resonancefrequency or induced voltage. In the unconnected state the magneticpowering is disabled, hence no interference is induced into the radiochannel, in the measurement or in metal parts in close proximity. In theconnected state, the flux is very well confined into the fluxconcentrators 203, 213, which also prevent interference. Disconnectingmay be detected by polling the opposite effect (by briefly switching offthe coil and observing the resulting effect).

ii) Secondly, due to the very short distance between the two antennas204, 214, the amplitude and SNR of the received RF signals increasessignificantly. The radio transmitters can now scot-free switch to anear-field mode by lowering their output power while maintainingconsistent data communication. Consequently, the radiated RF power inthe neighborhood is significantly reduced, which helps to freeing-up theradio spectrum. Furthermore, due to the efficient RF coupling, the powerconsumption of the radio is reduced.

It should be noted that RF coupling in the near-field mode, in which thedistance is a fraction of the wavelength, is more due to capacitivecoupling than far field EM waves. Both effects are validated on aregularly basis via a polling mechanism, or triggered by additionalproximity detection (optical, magnetic) or by a simple mechanical switchor a reed-switch.

To avoid stray flux a coil is preferably not powered fully(continuously) without counter-core present. However a polling mechanismmay generate power for a short time (e.g. 10 ms) every second to measuremagnetic coupling.

RF communication and/or data transfer via the magnetic coupling (as e.g.implemented in the Qi standard) or optical coupling is used to updateand negotiate IDs, required power, signal quality, charging status etc.before deciding to start nominal power transfer.

Below it will be described in more detail how the actualconnection/disconnection process triggers association in a patientnetwork and how safety is implemented.

Galvanic isolation is guaranteed by the PCB layer material and theC-core. Alternatively, extra isolation layers on top on the PCB 202, 212and the pole-tips of the C-core 203, 213 can be added. The unoccupiedarea of the PCB may be used for the measurement electronic and the PSC.Ferrite cores can be good conductors, but there are also highlyresistive (composite) ferrites available.

Alternative antenna configurations are possible, e.g. a ring shapedantenna 224 as shown in FIG. 11 depicting a top view of a seventhembodiment of a connector 220 for use in the system.

In the embodiments shown in FIGS. 10 and 11 the mechanical alignment ofthe connectors 200, 210, 220 is limited to two rotational orientationsin which the antennas and C-cores are aligned. This is a seriousdrawback when using cables in body-worn measurements and daisy chainconfigurations. This problem is solved by a rotational symmetricalconnector 230 as shown in FIG. 12 showing a cross-sectional view (FIG.12A) and a top view (FIG. 12B) of an eighth embodiment of a connector230 for use in the system.

The inner leg 232 of the E-core 231 (i.e. a core having a cross-sectionforming an E) carries the coil windings 201 for magnetic powering. TheRF antenna 204 is arranged in the PCB 201 between the inner leg 232 andthe outer legs 233 (which is actually a single ring as shown in FIG.12B). The legs 232, 233 are connected by a yoke 236. The inner or outerwalls of the core 231 may also be cladded with conductive material tofurther reduce interference. When two of such connectors are connected,the two halves form a pot-core where the magnetic field and the radiosignals are thus very well coupled and shielded. In addition, ameasurement unit 234 and a PCS unit 235 may be provided.

Alternatively, the RF antenna 204 is located outside the magnetic core231, i.e. around the outer legs 233, which may contribute to even lesscrosstalk and interference between the RF and magnetic signals. This isillustrated in FIG. 13 showing a cross-sectional view (FIG. 13A) and atop view (FIG. 13B) of a ninth embodiment of a connector 240 for use inthe system.

FIG. 14 shows a cross-sectional view (FIG. 14A) and a top view (FIG.14B) of a tenth embodiment of a connector 250 for use in the systemcomprising a rotational symmetrical C-core 251 forming a ring having aC-shaped cross-section formed by two legs 252, 253 connected by a yoke254. The magnetic flux generated by the coil 201 is indicated by arrows255. The RF antenna 204 is arranged between the inner legs 252 of theC-core 251.

FIG. 15 shows a cross-sectional view of an eleventh embodiment of aconnector 260 for use in the system, which is similar to the tenthembodiment shown in FIG. 14, but in which the RF antenna 204 is arrangedaround the outer legs 252 of the C-core 251.

The connectors shown in FIGS. 10 to 15 provide the advantage that theyare rotational symmetrical and that—in connected state—there is a verysmall gap between the connector and its counterpart connector.

FIG. 16 schematically depicts the layout of a connector 270 (such as theconnectors shown in FIGS. 10 to 15) for wireless transmission of dataand/or power between separate devices comprising such a connector. Theconnector 270 comprises a data transmission unit 271 (e.g. comprising anRF antenna 204) arranged for transmitting data to and/or receiving datafrom another device of the system having a counterpart connector,preferably by use of RF transmission. The connector further comprises amagnetic coupling unit 272 (e.g. comprising a coil 201 and a core 203)for transmitting power to and/or receiving power from another device ofthe system having a counterpart connector by use of inductive coupling.A detection unit 273 (e.g. comprising a power unit 207) is provided fordetecting the strength of magnetic coupling between the magneticcoupling unit 272 and a magnetic coupling unit of the counterpartconnector. A control unit 274 switches the data transmission unit 201into a low-power mode and/or enables the magnetic coupling unit 272, ifthe detected magnetic coupling is above a first threshold and/or itsincrease is above a second threshold. Further, the control unit 274switches the data transmission unit 271 into a high-power mode and/ordisables the magnetic coupling unit 272, if the detected magneticcoupling is below a third threshold and/or its decrease is above afourth threshold. The thresholds may be predetermined, e.g. derived froma simulation or from measurements. This embodiment enables the automaticsetting of the correct mode of the connector which particularlyminimizes power consumption, crosstalk and usage of RF bandwidth.

It should be noted that the detection unit 273 and the control unit 274disclosed in FIG. 16 may generally be used in all other connectorsdisclosed herein.

FIGS. 17 to 28 show a plurality of embodiments of a stackable connectorfor explaining details of such a stackable connector.

FIG. 17 schematically shows a first embodiment of a single stackableconnector 300 for use in the system, wherein FIG. 17A shows across-sectional view, FIG. 17B shows a top view, FIG. 17C shows a firstperspective view and FIG. 17D shows a second perspective view. FIG. 18schematically shows two stackable connectors 300, 300 a of the kind asshown in FIG. 17 stacked upon each other, wherein FIG. 18A shows across-sectional view, FIG. 18B shows a first perspective view and FIG.18C shows a second perspective view. The connector 300 comprises ahousing 301 and a magnetic coupling unit 302 arranged within the housing301 for transmitting power to and/or receiving power from another deviceof the system having a counterpart connector by use of inductivecoupling. Said magnetic coupling unit 302 includes a flux concentrator303 (preferably being rotational symmetrical, e.g. ring-shaped, and madeof high-permeable material), at least part of which having a U-shaped(or C-shaped) cross-section forming a recess 304 between the legs of theU. A first coil 305 is arranged within a recess 304 of the fluxconcentrator 303. A second coil 306 is arranged opposite the first coil305 and outside of the recess 304 in which the first coil 305 isarranged. The flux concentrator 303 may one of different possible forms,such as a ring-shaped form, a circular symmetrical form, the form of asquare, triangle, rectangle, etc.

Further, a ring-shaped RF antenna 307 (as part of a data transmissionunit) arranged inside of the flux concentrator, an RF unit 308(comprising radio electronics), a power unit 309 (such as magnetic powerelectronics) and a measurement unit 310 may be provided in or on the PCB312. In the second connector 300 a a battery 311 is provided instead ofthe measurement unit 310. Further, a PSC unit 313 may be provided in theconnector, as shown in FIG. 18C, for coupling with a sensor. The outersurface of the housing is preferably fully covered by isolated material(e.g. a plastic material) for galvanic isolation, watertight sealing andmechanical stability.

The housing 301 is arranged to allow stacking of two or more of suchconnectors 300, 300 a upon each other as e.g. shown in FIG. 18 so thatthe second coil 306 of the connector 300 and the first coil 305 a of thesecond connector 300 a (or vice versa, depending on the sequence inwhich the connectors 300, 300 a are stacked upon each other) stackedupon the connector 300 together form a first transformer for inductivepower transmission there between.

A circular bulge 314, 314 a formed on the top surface of the connectorsfits into the circular recess 304, 304 a on the bottom of the nextconnector. The upper coil 306 of the connector 300 together with thelower coil 305 a of the connector 300 a is thus enclosed byhigh-permeable magnetic material of the flux concentrators 303, 303 a.As a result said coils are now intimately coupled, which enablesefficient power transfer. The arrows 315 show the magnetic flux lineswhen said coils are actuated as indicated. In this way stray flux isminimized which avoids crosstalk to/from the measurements and the radiosignals. If needed conductive sheet material can be added toshort-circuit any remaining flux components.

All the components of the connector 300, 300 a including measurementunit, battery, cable connector (PSC unit) are preferably fitted intocircular shaped sealed box 301, 301 a representing the housing. Due tothe rotational symmetric design, no particular positioning of twoconnectors in radial direction is required for stacking, but in this wayconnectors can be easily stacked on top of each other. Beside thecircular shape other shapes are possible, e.g. with reduced rotationalangle, square shape, shapes with extension in four directions, etc.

Preferably, the pole-tips of the inverted U core are not covered with(thick) plastic, because this will negatively affect the efficiency andintroduce stray flux. Isolation can be guaranteed by reducing theplastic thickness, e.g. to a few tenth of a mm. Alternatively, galvanicisolation can be guaranteed though, because (composite) ferrite materialmay have a high intrinsic resistivity and internally the coils and themagnetic core can be isolated.

The transfer of magnetic power does preferably not start before a largecoupling between coils and RF is detected, as explained above withrespect to FIGS. 10 to 16. In the example shown in FIG. 18 only thelower coil 305 a and the upper coil 306 are used, the other coils arenot actuated at all.

For reasons of efficient power transfer and high radio SNR, the couplingareas should be large enough. Therefore, preferably, coils 305, 306, 305a, 305 b and RF antennas 307, 307 a are located on the outer area of therespective connector 300, 300 a.

The PSC unit 313 for connecting one or more sensors to the connector 300comprising a measurement unit 310 is preferably located on the side ofthe connector 300 in order to have full freedom of stacking. But the PSCunit 313 may also be located e.g. on the upper part of the connector 300when restricted to have always a connector 300 including a measurementunit 310 on top of the stack.

FIG. 19 shows three connectors 300, 300 a, 300 b stacked upon eachother, wherein the connectors 300, 300 b are identical and configured asshown in FIG. 17 and each comprise a measurement unit 310, 310 a,whereas the connector 300 a is configured as shown in FIG. 18 andcomprises a battery 311. The measurement units 310, 310 b are thus fedby the same battery 311 of the connector 300 a (hereby, the battery 311may also be located at a different position, e.g. at the bottom or topposition). In this case, both coils 305 a, 306 a of the connector 300 aare used to supply energy to the measurement units 310, 310 b. Manyvariations on this scheme are possible, e.g. receiving power from oneconnector via one coil and at the same time supplying power to anotherconnector via another coil.

The present invention is applicable for virtual any combination ofstacked connectors including in any kind of device used in a system ase.g. shown in FIG. 2, e.g. in a patient monitoring system. Hence, one ormore measurement modules, battery units, cable units and processingunits may be easily coupled for cordless transfer of power and/or data.It enables even chaining devices to each other. A daisy chain is e.g.valuable in body worn sensing to avoid cable cluttering by connectingdevices (e.g. measurement module) via one single connection or cable(comprising connectors) to a patient monitor, a powering device or ahub. This concept is illustrated in FIG. 20 showing the arrangement ofseveral devices in the form of a daisy chain, each device including oneor more of the connectors.

FIG. 20A shows a serial coupling of three measurement modules 30, 40, 80(e.g. of the kind as shown in FIG. 2) coupled in series and coupled to acentral processing unit 20 (e.g. of the kind as shown in FIG. 2). FIG.20B shows a cross-sectional view of a stack 320 of three connectors 381,352, 361 of the kind as shown in FIG. 17, wherein connector 381 is partof measurement module 80, connector 351 is part of a first cable unit350 and connector 361 is part of a second cable unit 360. The firstcable unit 350 comprises, at each of its ends, a connector 351, 352 andconnects the measurement module 80 with the measurement module 40 havinga connector 341 of the same kind. The second cable unit 360 comprises,at each of its ends, a connector 361, 362 and connects the measurementmodule 80 with the central processing unit 20 having a connector 321 ofthe same kind. A third cable unit 370 comprises, at each of its ends, aconnector 371, 372 and connects the measurement module 40 with themeasurement module 30 having a connector 331 of the same kind.

Hence, in this example, the measurement module 80 is connected to twocable units 350, 360. The cable unit 360 thus can transport power anddata for the complex of the three measurement modules 30, 40, 80 toand/or from the central processing unit 20. Data and power may berelayed, transferred and/or exchanged between the stacked connectors.Power transfer may be performed by using additional rectifier andtransmit electronics (e.g. DC/AC conversion), or by simply sharing ACcurrent between coils, which is the most efficient option in terms ofhardware.

It should be noted that the arrangement of the other stacks ofconnectors shown in FIG. 20A, e.g. of connectors 321 and 362 or ofconnectors 341, 351 and 372, is similar or identical as the arrangementof the stack 320 shown in FIG. 20B.

According to the same principle a star configuration is possible asshown in FIG. 20C instead of the series configuration shown in FIG. 20A.

It should be noted that combined power and data transport via the samecable is preferred, but alternatively any combination of short rangeradio cable and local batteries is also feasible.

FIGS. 21 to 23 show further embodiments of a stackable connector havingan alternative connector geometry compared to the connector geometryshown in FIG. 17. FIG. 21A shows a cross-sectional view of a circularconnector 390, in which the area outside the flux generator 303 isoccupied by measurement electronics 310 and/or a battery. FIG. 21B showsa top view of said connector 390. FIG. 22A shows a cross-sectional viewand FIG. 22B shows a top view of a rectangular connector 391. FIG. 23shows a smartcard sized connector 392 in a cross-sectional view (FIG.23A), a top view (FIG. 23B) and a simplified cross-sectional view (FIG.23C), which can be sandwiched between the walls of a patient monitorslot 27. Via coupling units 321, 393 the central processing unit 20 andthe connector 392 are coupled.

In an embodiment the upper and/or lower surfaces of the connector istotally flat. This makes e.g. cleaning easier. Corresponding embodimentsof a connector 400, 410 are shown in FIGS. 24 and 25. There are furtherembodiments possible with other alignment structures or features toensure exact positioning and tight alignment (preferably <1 mm) betweenthe flux concentrators of different connectors when stacked together.For instance, the gap (having a low μ) between flux concentrators(having a high μ; including plastic insulation of housing) should be<0.5 mm+/−0.1 mm in a particular application. Lateral displacementshould be small compared to geometry of poles (e.g. <0.5 mm).

FIG. 24 shows a cross-sectional view of a connector 400 (including ameasurement module 310), 400 a (including a battery 311) having ahousing 407, 407 a with flat main surfaces 408, 409, 408 a, 409 a usinga flux concentrator 401, 401 a having a cross section in the form of anH. Each flux concentrator 401, 401 a comprises a first (lower) recess402, 402 a, in which the first (lower) coils 305, 305 a are arranged,and a second (upper) recess 403, 403 a, in which the second (upper)coils 306, 306 a are arranged The lower coil 305 a of the connector 400a and the upper coil 306 of the connector 300 together the lower part ofthe flux concentrator 401 a and the upper part of the flux concentrator401 form a transformer, as indicated by the arrows 404.

FIG. 25A shows a cross-sectional view of a connector 410 (including ameasurement unit 310) having flat surfaces. A top view of the connectoris shown in FIG. 25B. The connector 410 comprises two flux concentrators411, 421, each having a U-shaped cross-section and each forming a recess412 and 422, wherein each recess is formed between two neighboring legs414, 415 and 424, 425 of the respective U, i.e. between the respectiveouter ring 414, 424 and the respective inner ring 415, 425 (which is acentral finger in this embodiment). A first coil 417 is arranged withinthe recess 412 of the first flux concentrator 411 and a second coil 427is arranged within the recess 422 of the second flux concentrator 421.

The two flux concentrators 411, 421 may also be seen as a commonH-shaped flux concentrator, in which the two legs 414, 415, 424, 425 ofthe H-shaped flux concentrator 421 are arranged adjacent to each otheror formed integrally and in which the transverse joint between the legsof the H is split into two joint elements 419, 429 with a shielding 418arranged there between and perpendicular to the legs 414, 415, 424, 425of the H.

The concept of stacking can also be converted to a lateral geometry.This is beneficial to reduce building height. A cross-sectional view ofan embodiment of a connector 430 having a lateral geometry is shown inFIG. 26A and a top view of the connector 430 is shown in FIG. 26B. Theconnector 430 comprises, separately at its left side and at its rightside, coils 431, 441 arranged in the recess 437, 447 of a respectiveflux concentrator 432, 442 (each having an U-shaped cross-section likethe flux concentrators 411, 421 shown in FIG. 25A). Around the fluxconcentrators 432, 442 ring-shaped RF antennas 433, 443 are arranged.Further, two power units 434, 444, two RF units 435, 445 two PSC units436, 446 and a measurement unit 310 are provided. The flux concentrators432, 442 are thus arranged laterally displaced with respect to eachother, so that the first flux concentrator 432 and the second fluxconcentrator 442 are arranged at opposite areas and adjacent to the samesurface of the housing. The housing 439 is preferably flat or has flatsurfaces.

FIG. 27 shows a daisy chain 440 formed between measurement modules 30,40, each comprising a connector 430 a, 430 b as shown in FIG. 26, by useof a cable unit 450 comprising connectors 430 c, 430 d as shown in FIG.26. FIG. 27A shows a cross-sectional view of the daisy chain, FIG. 27Bshows a top view. Such a cable unit 450 may comprise two or more of suchconnectors, preferably one at each end, but optionally additionalconnectors in between the ends.

FIG. 28 shows a body worn sensor arrangement 460 in a cross-sectionalview (FIG. 28A) and a top view (FIG. 28B). The body worn sensorarrangement 460 comprises a stackable support layer 461 carrying a cableunit 451, similar or identical to the cable unit 450 shown in FIG. 27,comprising connectors 452, 453, like the connectors 430 c, 430 d or withjust a single coupling unit as shown in FIG. 28A. On said cable unit oneor more measurement modules 30 and/or a battery module 90 (comprising abattery), each comprising a connector 430 a, 430 b, may be arranged.

Measurement modules 30, 40, 80, battery modules 90 and cable units 450can also be connected to e.g. a patient monitor or a central processingunit 20 using the same lateral geometry concept as schematically shownin FIG. 29. Further, any combination of vertical stacking and lateralconnection is generally possible with the connectors as proposed by thepresent invention. For instance, a measurement module may have bothvertical stacking and lateral stacking means.

In the following a battery module comprising a connector will bedescribed in more detail.

As described above, plug-in measurement modules are coupled to thecentral processing unit via the proposed connector using magneticpowering and RF data communication. In addition, via its RF channel abattery (or any other energy storage element) may be made part of thenetwork, e.g. a patient network, and may be coupled to other devices,such as measurement modules and the central processing unit in the samemanner. This is schematically illustrated in FIG. 30 showing a schematicdiagram of another embodiment of a system 13 including a measurementmodule 30, a central processing unit 20 and a battery module 90.

In a wireless measurement scenario the bi-directional battery module 90may be snapped onto the measurement module 30 to supply energymagnetically via the proposed connector. Optionally, the measurementmodule 30 itself may comprise a small buffer battery 37 (or any otherenergy storage element) for temporarily bridging the transition timebetween wired and wireless scenarios.

The battery module 90 preferably comprises a battery 91 (also calledbattery unit) and a coupling unit 92 for magnetic power transmissionbetween the battery module and other devices, e.g. to load the batterywhen the battery module 90 is coupled to the central processing unit 20and to load the battery 37 of the measurement module 30 when the batterymodule is coupled to the measurement module 30. Optionally, means fordata transmission may be provided in the battery module 90 as well.

A more detailed schematic diagram of a battery module 90′ for wirelessexchange of data and power between the battery module and another deviceof a system, in particular of a patient monitoring system, to which saidbattery module is coupled, is shown in FIG. 35. Said battery module 90′comprises a sealed housing 93, a battery unit 91 for storing electricalenergy, a data storage unit 94 for storing data, and a connector 95. Theconnector comprises a data transmission unit 96 for transmitting data toand/or receiving data from another device of the system having acounterpart connector and a magnetic coupling unit 92 for transmittingpower to and/or receiving power from another device of the system havinga counterpart connector by use of inductive coupling.

Optionally, a second connector 97 is provided for simultaneouslytransmitting data to and/or receiving data from two other devices of thesystem and/or for simultaneously transmitting power to and/or receivingpower from two other devices of the system.

The connector and its elements may be configured as explained above withrespect to other devices and other embodiments. This holds particularlyfor the magnetic coupling unit 92 and for the data transmission unit 96,which may be configured as disclosed herein, e.g. as shown in any one ofFIGS. 10 to 15 or 17 to 28.

The battery 91 may e.g. be a rechargeable battery, disposable battery ora super-capacitor and may be fitted into a smooth sealed plastic box,well protected for mechanical damage and fluids. It can be physicallyattached (i.e. put in close contact) to another device having a proposedconnector (e.g. measurement module, cable unit or patient monitor), e.g.via an easy to use snap on or slide-In mechanism. Permanent magnets oralignment structures may be used to align and fixate its position foroptimal power and radio transfer. When the battery 91 is empty, thebattery module 90 can be attached (optionally via the cable) to anydevice in the system having a compatible connector and being able tocharge, e.g. the patient monitor, a hub or a dedicated battery charger.Preferably, the same inductive/data connector topology is usedthroughout the whole architecture to couple all elements with eachother. This enables that batteries can be charged anywhere providing ahuge improvement on battery management.

Rechargeable battery life is almost always defined as number of fullcharge-discharge cycles by manufacturers and testers. In addition tocycling, the rate of degradation of lithium-ion batteries is stronglytemperature-dependent; they degrade much faster if stored or used athigher temperatures e.g. when applied to the human body.

Therefore, the health and charge condition of the battery may beconstantly determined from a temperature sensor, absolute time and thecharge- and discharge profiles by using the voltage and/or currentsensor(s), generally represented by sensor unit 98 in FIG. 35. On thebasis of this information and historical data a self-diagnosis may beperformed, which is communicated in the patient network to indicate theneed for re-charging, for replacement or any faulty condition.Historical data may be stored locally (e.g. in the battery module) aswell as shared in the network. Many scenarios are possible for thispurpose.

The battery module 90′ may further comprise a processing unit 99 fordata processing of received data, time keeping, self-diagnosis andsafety. Said processing unit may further be configured to calculate anexpected operation time when applied to a measurement module 30.

Still further, the battery module 90′ may, as illustrated in FIG. 16,comprise a detection unit 273 for detecting the strength of magneticcoupling between the magnetic coupling unit and a magnetic coupling unitof another device, and a control unit 274 for switching the datatransmission unit into a low-power mode and/or for enabling the magneticcoupling unit, if the detected magnetic coupling is above a firstthreshold and/or its increase is above a second threshold, and forswitching the data transmission unit into a high-power mode and/or fordisabling the magnetic coupling unit, if the detected magnetic couplingis below a third threshold and/or its decrease is above a fourththreshold.

The main standards in wireless power transfer are the Qi standard andthe Power Matters Technology (PowerMat) standard. Their main applicationis in the field of wireless charging. Qi comprises also a basiclocalization and recognizing mechanism for devices, low-power standbymode and power control.

An additional on-off switch using reed-contacts and a permanent magnet(e.g. the one present as part of the click-on fixation mechanism) may beuseful as an extra layer of safety and battery leakage prevention, butthere may also be other means for stacking detection, e.g. optical,capacitive or ultrasound means.

Li-ion and Li-polymer batteries are favorite candidates because of theirhigh energy density per unit of mass and its large scale of use in theconsumer domain. They have electronics means in place to watch itscharge condition and protect from over-heating. Also the Qi standard hasalready some basic means in place to recognize valid loads. These may beused. These basic protection and monitoring means may be integrated intothe complete architecture by combining magnetic and RF coupling ascommunication means, local intelligent safety monitoring and byconnection to a patient network. For example, the absence of a valididentifier and/or the presence of a local failure condition may be areason to abandon or not to start magnetic power transfer.

The charge status may be used to determine how long a battery can beapplied for a particular measurement. This can be shown on e.g. thepatient monitor display. Optionally, when attached to a measurementmodule, a visual or audio indicator on the battery itself may indicatewhen e.g. the available measurement time is less than 1 hour beforereplacement or charging should take place.

Integrating batteries in a medical setting as described above hasserious consequences on safety, use case and workflow. Constraintsinclude absolute safety, possible shape, less weight and size, easyreplaceability/swappability by the nurse, easy cleanability, largecapacity, and chargeability during wearing. Battery modules may beclosed boxes, fully wirelessly connected for both charging as forsupplying energy. The proposed architecture offers easily cleanablemechanical connections. Furthermore, they can be replaced within a fewseconds while the measurement device stays in place.

In the following a cable unit comprising connector for connecting otherdevices of a network/system will be described in more detail.

A general layout of a cable unit 500 is shown in FIG. 31. The cable unit500 comprises a cable 510 and a connector 520, 530 at each end of thecable 510. Each connector 520, 530 comprises a magnetic coupling unit521, 531 and a data transmission unit 522, 532. The cable 510 comprisesa first wire pair 511 (e.g. twisted wires) connecting the magneticcoupling units 521, 531 and a second wire pair 512 (e.g. twisted wires)connecting the data transmission units 522, 532.

FIG. 32 illustrates the use of a cable unit 500 in a high acuitysetting, in this example for connecting a measurement module 30 and acentral processing unit 20. Such a cable unit 500 may be used in an OR(operation room) or ICU (intensive care unit) setting to guarantee dataintegrity and power consistency for the measurement. The two wire pairs511, 512 are preferably thin and flexible as used in cathetertechnology. Extra conductive shielding or ferrite common mode coils maybe added for extra robustness and performance. This approach guaranteesa sufficient high signal to noise ratio for the radio signal due to itslow RF attenuation and shielding properties. Due to the large ratiobetween the frequencies for contactless powering (100-200 kHz) and theradio (2.4 GHz) the internal crosstalk is manageable.

Many options are possible for implementing the main functionality ofthis cable unit 500 to form a protected pipe for the radio- andpower-signals.

One option is a fully passive cable unit comprising two wire pairs (asshown in FIGS. 31, 32). Basically RF data and power can be transferredin two directions across the cable unit. Twisted wires for power and acoaxial- or balanced transmission line for RF data may be used.Additionally, passive components may be added to the connector tofurther improve RF transmission by e.g. filtering and impedancematching, to improve (power) transfer by e.g. flux concentrators or forpassive identification (optical tag).

Optionally, power and radio signals may be combined in one single wirepair (or coax cable). Attaching only one connector of the fully passivecable to e.g. a measurement module will neither increase the magneticcoupling nor the RF coupling. Two connections are made until pairing isinitiated.

Another option is an active cable. Active components are present (in oneor both connectors) to convert the magnetic power signals toclean/stabilized DC or sinusoidal AC before sending them across thecable. This limits crosstalk and disturbances from the power signal intothe radio channel. The most logical location of said components is inthe connectors(s), but they can also be distributed across (a part of)the cable unit, e.g. on a flexible foil integrated in the cable sleeve.

The data radio signal may be amplified, re-modulated (transponder),buffered or (actively) impedance converted to match the RF cableproperties. Alternatively, conversion to another frequency band or tobaseband may enhance signal integrity even more, for example byconversion to a serial bus format like e.g. USB, RS232 or TCP/IP. A partof the magnetic power is used to power said active components.

Each connector may be arranged and act in itself as a node and be a partof the patient network, including unique identifier, radio and networkstack for pairing as well as magnetic powering. Additional radios may beadded to relay radio signals (e.g. in a daisy chain) or to implementseparate channels for patient network management. Active cables maytransport data or power in only one direction; hence, more wire pairsper cable or more cables may be needed to transport in both directions.

According to another option conversion of the RF signal to the opticaldomain may be provided, which offers the ultimate level in dataintegrity and potentially also allows for a thinner cable.

Obviously, cables units may comprise solely power or data channels.

Identification tags (RFID) or a radio unit may be added to the cableunit or the connectors for identification and data management.

Preferably, from a user perspective, the cable unit should be able totransport RF data and power in two directions. This may need to use morewire pairs, e.g. in case when active components are applied.

FIG. 33 illustrates the use of a cable unit 500 in a lower acuitysetting, in this example for connecting a measurement module 30 (orbattery module 90) and a central processing unit 20 only when needed forimproving RF performance (e.g. in crowded areas), or for powering orcharging reasons (i.e. saving battery capacity for mobile use).Measurement modules may be connected in a chain to avoid cablecluttering.

A more detailed schematic diagram of a cable unit 500′ for connectingdevices in a system, in particular in a patient monitoring system, toenable wireless exchange of data and/or power between them, isschematically shown in FIG. 36. As explained above, the cable unit 500′comprises a cable 510 and a connector 520, 530 arranged at each end ofsaid cable. Each of said connectors comprises a data transmission unit522, 532 for transmitting data to and/or receiving data from a devicehaving a counterpart connector and a magnetic coupling unit 521, 531 fortransmitting power to and/or receiving power from another device of thesystem having a counterpart connector by use of inductive coupling.

The cable unit 500′ further comprises a (sealed) housing 523, 533arranged at each end of the cable 510, in which the one or moreconnectors 520, 530 arranged at the respective end of the cable arearranged. The sealed housing is preferably configured as disclosedherein in the context of other devices to allow stacking of the cableunit 500′ to other devices having a counterpart connector.

The connector and its elements may be configured as explained above withrespect to other devices and other embodiments. This holds particularlyfor the magnetic coupling units 521, 531 and for the data transmissionunits 522, 532, which may be configured as disclosed herein, e.g. asshown in any one of FIGS. 10 to 15 or 17 to 28.

The cable unit 500′ may further comprise electronic circuitry 501 fordata processing, conversion and/or storage of received data.

Further, the cable unit 500′, in particular each connector 520, 530,may, as illustrated in FIG. 16, comprise a detection unit 524, 534 fordetecting the strength of magnetic coupling between the magneticcoupling unit (of the respective connector) and a magnetic coupling unitof another device, and a control unit 525, 535 for switching the datatransmission unit (of the respective connector) into a low-power modeand/or for enabling the magnetic coupling unit (of the respectiveconnector), if the detected magnetic coupling is above a first thresholdand/or its increase is above a second threshold, and for switching thedata transmission unit (of the respective connector) into a high-powermode and/or for disabling the magnetic coupling unit (of the respectiveconnector), if the detected magnetic coupling is below a third thresholdand/or its decrease is above a fourth threshold.

As an alternative option, the cable unit 500′, in particular eachconnector 520, 530, may comprise a proximity detector 526, 536 fordetecting proximity of the cable unit of another device (i.e. fordetecting if there is only a small air gap in between) and a controlunit 527, 537 for switching the respective data transmission unit 522,532 (of the respective connector) into a low-power mode and/or forenabling the magnetic coupling unit (of the respective connector), if adevice is detected to be proximate to the cable unit, and for switchingthe data transmission unit (of the respective connector) into ahigh-power mode and/or for disabling the magnetic coupling unit (of therespective connector), if no device is detected to be proximate to thecable unit. Such a proximity detector and control unit may also be usedin other embodiments of the connector and in other devices disclosedherein.

Various methods of proximity detection may be used, e.g. received signalstrength indication (RSSI) methods such as standard Bluetooth, BluetoothLow Energy (BTLE) and Wi-Fi. Other example methods of proximitydetection include differential methods such as ultra-wideband (UWB),optical methods using at e.g. infrared (IR) wavelengths ultrasound andNFC. Proximity detection methods such as IRDA, UWB and NFC typically useboth standard and proprietary data transport mechanisms. In examples,proximity detection may occur when two devices are e.g. within a rangeof 0.5 mm+/−0.1 mm of each other, whereby other distances may be used.

Generally, direct or indirect means for detecting proximity of thedevice to another device may be used. The actual distance between twodevices that can be detected as “proximate” depends e.g. on the magneticdesign; one criterion may be if the magnetic coupling is larger than 90%or preferably larger than 95%, or ultimately larger than 99%. In anexemplary design a magnetic distance of ˜0.5 mm+100 μm (due to 2*0.25 mmplastic housing) is used, which may be understood as “close proximity”.However, other distances may be used instead, depending on theparticular design and/or application.

Finally, within each housing 523, 533 a second connector 540, 550 may bearranged for simultaneously transmitting data to and/or receiving datafrom two devices and/or for simultaneously transmitting power to and/orreceiving power from two devices. Said second connectors 540, 550 aregenerally configured in the same way as the first connectors 520, 530.

The proposed cable units may be used for mutually connecting measurementmodules and monitoring devices. Daisy chains as well as starconfigurations, as shown in FIGS. 20A and 20C are possible. Cables unitsmay be coupled laterally or vertically, on top of each other or with athird component in between. Alternatively, a distribution cable unit mayhave multiple branches to connect components physically.

In the following the pairing of devices will be explained.

A first option of pairing is to perform pairing manually, e.g. duringthe attachment of a measurement module to a person's body. By bringing adevice physically in close proximity with another, identifiers areexchanged, which effectively means that said device is added into thenetwork of devices, e.g. into the patient network. This is easy toachieve during first time attachment of the measurement module and formobile patients.

The order of connecting is generally not important; every member of thenetwork can communicate and update the network status, e.g. via a masterdevice in particular standards, like Bluetooth-LE. Visual or audibleinformation on the devices may indicate its connection status. It maye.g. indicate which devices are paired into a patient network, and itmay indicate loss of RF connectivity to a hospital network or patientmonitor of e.g. a mobile patient. In such a case the patient networkneeds to (automatically or manually) re-connect to another radio link.

The association mechanism starts when two conditions are met:

1. An increased level of magnetic coupling, which can be detected fromthe induced voltage in the secondary coil as well as the current in theprimary coil or the resonance frequency of the assembly. When thiscondition is met, the RF radios start communicating with each other(could be via the master device).2. When the strengths of the received RF signals are also above apre-determined level, associating is started. Alternatively, deviatingtransmitter antenna impedance (voltage standing wave ratio VSWR,reflected waves) can be included as an extra check, indicating RFabsorption of the transmitted signal.

Repeating this mechanism toggles the membership of a patient network,i.e. the master device knows all devices in the network of the specificpatient; it switches between joining and leaving. Network membership maybe shown by visual, tactile or audible actuators (e.g. LED, display,buzzer, beeper, vibrator, etc.). Additionally, a mechanical switch orkeyboard code may be used to force leaving the network.

The patient may have plasters comprising patient-network functionalityas extra identification- and localization means, to enforce that ameasurement (or sensor) is attached on the correct position on thecorrect patient.

A second option of pairing is to connect immobilized (e.g. OR or ICU)patients to a patient network by use of a cable unit 500 as shown inFIG. 31. By connecting the cable unit between a measurement module and amonitoring device for a short time, the magnetic coupling and the RFamplitude will increase above a certain level, which triggers thepairing mechanism.

A third option of pairing is to use a contactless storage module, whichmay be used as an intermediate storage container to transfer identifiersbetween components in the patient network. This is illustrated in FIG.34 showing a schematic diagram of a fifth embodiment of a system 14comprising a storage module 95. By bringing the contactless storagemodule 95 in close proximity of another component 20 or 30 having acounterpart connector the identifiers are interchanged and used toupdate the patient network. An additional mechanical push button orproximity detector may be used to trigger exchange. Preferably, only oneidentifier can be stored and transferred to avoid unambiguity.

The contactless storage module 95 can have the form-factor of a pencil,a smart-card or a small box like the measurement modules. Like otherdevices comprising a connector, it comprises, besides a storage element98, a magnetic coupling unit 96 and a data transmission unit 97 (e.g.radio hardware) to couple to other devices having a counterpartconnector.

A fourth option of pairing is to use additional trigger means. A pushbutton or proximity detector (e.g. using optical, magnetic, ultrasoundtechnology) may be added as a condition to initiate the pairing process.Additional trigger means are beneficial as an extra layer of robustnessto omit components to detect the level of coupling (e.g. no RF ormagnetic coupling measurement). Further, in case of a pencil-likedevice, the RF antenna and coil may be located in the tip; the maximumcoupling may be below the predetermined threshold for triggering theassociation process.

A more detailed schematic diagram of a device 600 for wirelesstransmission of data and/or power between the device and another deviceof a system, in particular of a patient monitoring system, is shown inFIG. 37. Said device 600 is configured to apply the above describedapproach for pairing and comprises an identification unit 601 forstoring a unique identifier of the device and a connector 602. Saidconnector 602 comprises a data transmission unit 603 arranged fortransmitting data to and/or receiving data from another device of thesystem having a counterpart connector, a magnetic coupling unit 604 fortransmitting power to and/or receiving power from another device of thesystem having a counterpart connector by use of inductive coupling, anda detection unit 605 for detecting the strength of magnetic couplingbetween the magnetic coupling unit and a magnetic coupling unit of acounterpart connector of another device and for detecting the intensityof data received by the data transmission unit from a data transmissionunit of the other device.

The device 600 further comprises a control unit 606 for controlling thedata transmission unit 603 to transmit the unique identifier of thedevice to the other device and/or to receive the unique identifier ofthe other device, if a) the detected intensity of received data is abovea data intensity threshold and/or its increase is above a data intensityincrease threshold and b) the detected magnetic coupling is above amagnetic coupling threshold and/or its increase is above a magneticcoupling increase threshold.

The device 600 may further comprise a storage unit 607 for storingunique identifiers of other devices received by the data transmissionunit.

The control unit 606 may be configured to control the data transmissionunit to additionally transmit unique identifier of other devices storedin the storage unit and/or to receive unique identifier of otherdevices, if a) the detected intensity of received data is above a dataintensity threshold and/or its increase is above a data intensityincrease threshold and b) the detected magnetic coupling is above amagnetic coupling threshold and/or its increase is above a magneticcoupling increase threshold.

The detection unit 605 may be configured to detect impedance, resonancefrequency and/or induced voltage for detecting the strength of magneticcoupling and/or to detect signal intensity and/or antenna impedance ofan antenna of the data transmission unit for detecting the intensity ofreceived data. The strength of magnetic coupling is often referred to asmagnetic coupling factor k (0<=k<=1).

In case components are already connected, this is clear from theavailability of power and strong RF signal. Attachment of a newcomponent may be detected by use a polling mechanism to check theincrease of magnetic coupling (and, optionally, an RF signal used fordata transmission. Detection of disconnecting components may beperformed by the inverse process: a polling mechanism to measure adecrease of the strength of magnetic coupling by use e.g. of impedance,resonance frequency and/or induced voltage (and, optionally, of the RFsignal). Optionally, the RF signal strength may be measured in addition.

Generally, a first transmission of the unique identifier is interpretedas a request to couple the device with the system and a secondtransmission of the unique identifier is interpreted as a request todecouple the device from the system.

The device may further comprise an indicator 608, in particular avisual, tactile or audible indicator, for indicating the coupling statusof the coupling of the device with the system.

Still further, the device may comprise a user interface 609 for enablinga user to initiate a transmission of the unique identifier or a couplingor decoupling request message.

Still further, the device may comprise a proximity detector 610 fordetecting proximity of the device to the other device, wherein saidcontrol unit is control the data transmission unit the transmit theunique identifier of the device to the other device and/or to receivethe unique identifier of the other device, if additionally proximity ofthe device to the other device is detected. The proximity detector maybe configured as explained above with respect to other embodiments.

The connector 602 and its elements may be configured as explained abovewith respect to other devices and other embodiments. This holdsparticularly for the magnetic coupling unit 604 and for the datatransmission unit 603 which may be configured as disclosed herein, e.g.as shown in any one of FIGS. 10 to 15 or 17 to 28.

Finally, the device 600 may further comprise a data unit 611 forgenerating and/or receiving data, and/or a power unit 612 for supplyingand/or consuming power.

In the disclosed architecture it is foreseen to pass-through AC powerfrom a power source (battery/cable) to stacked modules without anyfurther processing (without re-modulation). The frequency of said powersignal is thus always available in all modules and may serve as a masterclock to derive timing pace locally. Additionally, the moment in timewhen modules (measurement modules, cable modules, battery modules) arestacked is a one-time trigger to (re)set the relative time betweenmodules. Obviously, the radio channel may also be used to generate aone-time trigger signal. This concept will be further described in thefollowing.

FIGS. 38A and B show different views of a first embodiment of a deviceaccording to the present invention, in particular a top view (FIG. 38A)and a side view (FIG. 38B) of a battery module 700 a. FIGS. 39A and Bshow different views of a second embodiment of a device according to thepresent invention, in particular a top view (FIG. 39A) and a side view(FIG. 39B) of a measurement module 700 b. FIGS. 40A and B show differentviews of a third embodiment of a device according to the presentinvention, in particular a top view (FIG. 40A) and a side view (FIG.40B) of a cable module 700 c.

The different modules 700 a, 700 b, 700 c shown in FIGS. 38, 39 and 40each comprise a connector 701. The connector 701 comprises a datatransmission unit 703 arranged for transmitting data to and/or receivingdata from another device 700 a, 700 b, 700 c of the system having acounterpart connector, and a magnetic coupling unit 702, 704 fortransmitting power to and/or receiving power from another device 700 a,700 b, 700 c of the system having a counterpart connector by use ofinductive coupling using a high frequency power signal. A detection unit705 is provided for detecting coupling of a counterpart connector ofanother device of the system with the connector 701. A control unit 707uses the detection that a counterpart connector of another device of thesystem has been coupled with the connector 701 as a trigger to determineand/or reset a relative time difference between a clock signal used bythe device and a clock signal of the other device using the highfrequency power signal of the magnetic coupling unit 702, 704 and amagnetic coupling unit of the counterpart connector and/or using areceived time calibration signal for determining and/or resetting therelative time difference.

In an implementation the modules 700 a, 700 b, 700 c each comprise acoil 704 (for inductive power transfer), a rectification section andconverters for stable voltage(s) and power generation and at least oneradio (BT4, BLE, Wi-Fi, ZigBee, etc.). The battery 706 of the batterymodule 700 a can be charged and discharged in a contactless manner. Anembodiment with devices coupled when they are in close proximity will bedescribed first.

When a battery module 700 a is connected wireless to a patient monitor(by radio or NFC or by module detection), a patient ID and time stamp ofthe monitor are assigned to the battery module 700 a. Next a measurementmodule 700 b (e.g. for ECG) is added to the battery module 700 a suchthat the coils 704 in the modules 700 a, 700 b are aligned and are inclose proximity (the alignment accuracy depends on the type of coil use,for an air coil the requirements are relaxed (e.g. in the range of mm tocm), for a coil with a high magnetic permeability alignment is in thesub mm range). Now power can be transferred between the modules 700 a,700 b and the presence of the second module is detected by the firstmodule.

This detection can be either by a magnetic, electric or optical means.The time of detection of module can be used as a time stamp and can bestored in a master device of the wireless system (in this example thebattery module 700 a). For the power transfer an AC signal withfrequency in the order of 100 kHz may be used. Since this power signalis identical for module 700 a and 700 b it can serve as a relative timemeasurement by for instance using a simple counter. Drifts in thisfrequency are of importance for absolute time but not for the relativetime which is within one cycle the same for the modules (<10 μs error).

Adding a second measurement module can be done in a similar method asfor the first measurement module, e.g. by stacking this module on top ofthe battery module or the first measurement module 700 b. The samestacking detection mechanism can be employed for detection of the secondmeasurement module and this can serve as a third time stamp for secondmeasurement module. Again this time stamp number 3 can be stored in themaster device (here the battery module 700 a).

Data is sent wirelessly from the measurement module(s) to the batterymodule and via the battery module to the monitor (can also be directlyto monitor). The data blocks contain information of the type ofmeasurement, channel information, information on measurement settings(signal processing delays), the time stamp and (relative time) countervalue of the first measurement byte. Data can be submitted for instancein four blocks each containing 20 bytes consisting partly of ID andinformation and measurement data and parameters (like heart rate, SpO2value, etc.). Data is received in the monitor where it is furtherprocessed, more complex parameters may be extracted and waveforms andparameters may be plotted on the display.

As shown in FIGS. 39A and B, the measurement module 700 b furthercomprises a galvanic connection unit 709 for galvanic coupling of themeasurement module 700 b to a third device 810, e.g. a sensor, having acounterpart galvanic connection unit 811. Further, a patient sideconnection unit 708 may be provided for connecting the device to one ormore sensors 810 to receive one or more physiologic sensor signals. Thesensor 810 may e.g. be an ECG sensor comprising a sensor element 813(e.g. ECG electrode) connected to the counterpart galvanic connectionunit 811 (also called sensor connector) via a lead wire 812.

The cable module 700 c further comprises a cable 710, which may beprovided at its other end (not shown) with another connector (like theconnector 701) for coupling the cable module 700 c with other modules orwith a monitor.

In another preferred embodiment one battery module powers at least twostacks of measurement modules in different locations on the body. Again,one common power signal dictates the timing pace, while stackingdetection or radio-messages are used to one-time trigger (re)set of therelative time difference. FIG. 41 shows a schematic diagram of a firstembodiment of a system including different devices according to thepresent invention. In this embodiment there is only one battery module700 a in the system. The second measurement module 700 b 2 of twomeasurement modules 700 b 1, 700 b 2 (each connected to a respectivesensor 810 a, 810 b) is powered by a data/power cable module 700 c(having a connector 701 at each end) that is connected to thecombination of battery module 700 a and measurement module 700 b 2.

Battery module 700 a and the first measurement module 700 b 2 are pairedto the monitor and each other in the same way as described above withreference to FIGS. 38 to 40. The second measurement module 700 b 1 isconnected to the battery module 700 a via a shielded cable module 700 cthat can have a two way transfer of a radio signal and power. Thedetection of the cable module 700 c at site 1 and site 2 can be done inthe same way as described above giving the time stamp 2. The radio inthe master can be used to send a message to the two devices for absolutetime calibration (this could also replace the time stamp obtained fromthe stacking detection). Again the power signal is identical for bothmeasurement modules and the battery module so that an accurate relativetime of measurement data is obtained.

In another preferred embodiment at least two battery modules 700 a 1,700 a 2 are connected to least two stacks of measurement modules 700 b1, 700 b 2 in different locations on the body, connected by the cablemodule 700 c. Such an embodiment is illustrated in FIG. 42 that shows aschematic diagram of a second embodiment of a system including differentdevices according to the present invention.

There are two options: Only one battery module is enabled to power allstacks of measurement modules and dictates the timing pace, or eachstack is powered by its own battery module and the cable moduledistributes the power signal (not the power) from one stack to anotherto dictate the timing pace.

This embodiment differs from the embodiment shown in FIG. 41 since thereis more than one battery module in the system. This complicates thesystem as there are now two different power signals which differ inphase and frequency. Both can change in a different way due totemperature changes etc. The cable can be applied to both devices,giving a new common time stamp. One of the two battery modules 700 a 1,700 a 2 is switched off (i.e. could be the one with the largestremaining energy), hence there is only one battery module active in thesystem. Relative time measurement is then similar to the above twoembodiments. When the battery energy is below a predetermined level(i.e. 30%) this battery module can be switched off and the other batterymodule takes over. This is a new time stamp, now the power clock signalof the second battery module is used for relative time.

FIG. 43 shows a schematic diagram of a third embodiment of a systemincluding different devices according to the present invention. In thisembodiment there are multiple nodes, each powered by a separate batterymodule 700 a 1, 700 a 2. For practical reasons the continuous use of acable between modules as in the embodiment shown in FIG. 42 is notpossible (i.e. mobile patient). The cable can be used for a short timeto generate a time stamp. The battery modules 700 a 1, 700 a 2 each willhave a slightly different and variable frequency so the tight relativetime requirements cannot be met.

A possible method would be to use a master clock signal (could be radio,optical sound) so that each module determines its time from this masterclock. This would require additional hardware which would drive cost up.Another method would be to use one of the radios as a master and let themaster emit a common short message to the slaves to generate a timestamp. The time of a message received in each module will have anidentical delay and this time can serve as a time stamp. Since typicalpower clock stability is around 100 ppm and assuming that the 100 ppmdrift can occur in a period of seconds this time stamp would be repeatedevery second for an error of less than 0.1 ms. This would requirefrequent radio contact which could degrade data rates and increasespower consumption. A preferred method is described below.

The highest time synchronization is needed for signals that are relatedto a heartbeat (ECG, IBP, SpO2). The heart rate is a patient specificparameter that can be used as an independent clock to calibrate theinternal clocks of each measurement to the one master clock in thesystem. Note that the heart rate is variable and specific for a certaintime interval (e.g. a few minutes). The physiologic signal and itsvariation can be used for accurate clock calibration by for instancecomparing average heartrate over periods of minutes or by comparingbeat-by-beat patterns (auto-correlation).

In another embodiment a bedside container module with severalmeasurement modules and one cable to the monitor is provided. This isone module that contains several measurement modules. The power clock isidentical for each measurement module. At insertion of a measurement itis detected automatically and a time stamp is generated at the detectiontime. Since the module is connected to the monitor via a cable, thesystem time from the monitor device can be used for absolute time.

In another embodiment the heart rate may be used as common clock todictate pace. Virtually all measurements (SpO2, ECG, NIBP, invasivetemperature, etc.) also determine the local heartbeat of the patient,which can be used as a global clock signal to dictate the pace of therelative timing between measurements. Timing noise can be smoothened bylocal PLL or FLL functionality e.g. inside each measurement.

Still another embodiment uses local correction. In this embodiment everymodule has its own crystal clock for determining the timing. By firstconnecting modules (as described in previous embodiments) deviations ofeach crystal with respect to the distributed master clock can becalculated. Next, modules are disconnected and said deviation is used tocorrect the timing accordingly. This assumes that temperature drift ofcrystal clocks is equal for all of them and drift rate variation issmall.

According to another embodiment synchronization is achieved byoccasionally sampling power pulse counters. In this embodiment eachmodule simply continuously counts the number of power pulses on (each ofits) input/output power transformers. Each counter resets to zero whenthe module powers up and/or when its corresponding power signal isinterrupted and/or on another externally generated synchronizationevent. This mechanism ensures that the counter values on both sides ofthe transformer formed by two stacked modules are always identical, eventhough in some of the cases the two counters in a single module may havedifferent values (to be discussed in the next embodiment). The modulenow occasionally registers a counter value together with its internaltime stamp. This information is very similar to a synchronizationexchange between two units with a packetized data link. The counters donot need to have a very large range. A synchronization algorithm likedescribed in Section 4.3 of Plomp et al., “Considerations forSynchronization in Body Area Networks for Human Activity Monitoring, IntJ Wireless Info Networks 18 (2011): 280-294 can be implemented with verylow resources—either in the module itself, or in a central receivingunit that collects the information—and is sufficient to reconstructaccurately the phase and frequency relation between the power signal andthe module's internal clock.

In another embodiment local synchronizations are linked in a chain. Inthis embodiment there is no requirement of a single power beat signalcoming from a single power source that passes through multiple modules.Each module can decide to pass the incoming power signal to a nextneighbor, or block it (because the neighbor is already powered andtrying to supply the module from the other side), or regenerate a newpower signal with different frequency and phase. Assuming that thesystem knows which module/side shares a direct power connection withwhat neighbor module/side, the relative phase and frequency relationbetween all neighboring module clocks can be reconstructed in thefollowing manner:

1. Reconstruct the phase and frequency relationships between a module'sinternal clock and the power signals on both sides, e.g. in the mannerdescribed in the previous embodiment.2. Power signals on both sides of a transformer formed by two stackedmodules are always identical, the relative phase and frequencyrelationship between neighboring modules can now also be established.

FIGS. 44A and B show different views of a fourth embodiment of a deviceaccording to the present invention, in particular a top view (FIG. 44A)and a side view (FIG. 44B) of a module 700 d. The module comprises astorage unit 711 for storing the moment of detection that a counterpartconnector of another device of the system has been coupled with theconnector 702 as a time stamp. The data transmission unit 703 may thentransmit the time stamp and/or a determined relative difference betweenthe clock signal used by the device and the clock signal of the otherdevice to the other device for storage in a master device of the system.

Further, in this embodiment the module 700 d further comprises a clockunit 712 for generating the clock signal used by the module. Further, acounter 713 may be provided for counting the number of pulses of thehigh frequency power signal, wherein the counted number is used forcalibrating the clock signal used by the module. The counter may resetto zero when the device is coupled to or decoupled from another deviceor when the inductive coupling is interrupted or when an externalsynchronization event is detected.

FIG. 45 shows a schematic diagram of another embodiment of a systemincluding different devices according to the present invention. Inparticular, a battery module 700 a and a monitor 800 are shown which maybe coupled wirelessly. The monitor 800 comprises a connector compatiblewith the connector 701, including a data transmission unit 803 and amagnetic coupling unit 802, 804.

FIG. 46 shows a schematic diagram of still another embodiment of asystem including different devices according to the present invention.In particular, a measurement module 700 b and a third device 820including a counterpart galvanic connection unit 821 are provided thatare galvanically coupled, for instance to receive a master clock signalfrom the third device 820 for calibrating the clock signal used by themeasurement module 700 b.

One main advantage of the present invention is that a universal approachis provided that may generally serve all patient monitoringapplications, which is a key factor to achieve in efforts to reducecosts. Further advantages are the modularity and the direct complianceto existing connectivity standards for wireless measurements.

The application of the present invention is not limited to patientmonitoring, but can be extended to mutually isolate modules (sensors,actuators) connected to a common entity in e.g. automotive or cattlebreeding (central milking machines connected to multi-cows). Further,the present invention is not limited to the explicitly disclosed types,forms and numbers of antennas or coils, which are to be understood asexamples only. Components used in the disclosed embodiments may also beconfigured as being compliant with the Qi standard or other wirelesspower standards, and also standard components compliant with the Qistandard may be used for single components according to the presentinvention, if possible from a technical point of view. Further, a devicemay comprise means for vertical and horizontal stacking and includecorresponding coupling means for coupling in the respective direction,i.e. a device may e.g. comprises a combination of the connectors asshown in FIGS. 25A and 26A.

The present invention can be applied for dielectric isolated wearablevital sign wireless sensor devices where time synchronization betweensignals needs to meet tight limits. Potential applications are inpatient monitoring, low acuity monitoring, wearables, continuous bloodpressure, etc.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, such illustration and descriptionare to be considered illustrative or exemplary and not restrictive; theinvention is not limited to the disclosed embodiments. Other variationsto the disclosed embodiments can be understood and effected by thoseskilled in the art in practicing the claimed invention, from a study ofthe drawings, the disclosure, and the appended claims.

In the claims, the word “comprising” does not exclude other elements orsteps, and the indefinite article “a” or “an” does not exclude aplurality. A single element or other unit may fulfill the functions ofseveral items recited in the claims. The mere fact that certain measuresare recited in mutually different dependent claims does not indicatethat a combination of these measures cannot be used to advantage.

Any reference signs in the claims should not be construed as limitingthe scope.

1. Device for wireless transmission of data and/or power between thedevice and another device of a system, in particular of a patientmonitoring system, said device comprising: a connector comprising a datatransmission unit arranged for transmitting data to and/or receivingdata from another device of the system having a counterpart connector,and a magnetic coupling unit for transmitting power to and/or receivingpower from another device of the system having a counterpart connectorby use of inductive coupling using a high frequency power signal, adetection unit for detecting coupling of a counterpart connector ofanother device of the system with the connector, and a control unit forusing the detection that a counterpart connector of another device ofthe system has been coupled with the connector as a trigger to determineand/or reset a relative time difference between a clock signal used bythe device and a clock signal of the other device using i) the highfrequency power signal of the magnetic coupling unit and of a magneticcoupling unit of the counterpart connector and/or ii) a received timecalibration signal for determining and/or resetting the relative timedifference, and a storage unit for storing the moment of detection thata counterpart connector of another device of the system has been coupledwith the connector as a time stamp.
 2. Device as claimed in claim 1,wherein the detection unit is configured to detect coupling of acounterpart connector in a magnetic, electric or optical manner. 3.Device as claimed in claim 1, wherein the detection unit is configuredto detect coupling of a counterpart connector by detecting if thestrength of magnetic coupling between the magnetic coupling unit and amagnetic coupling unit of the counterpart connector exceeds a magneticcoupling threshold, in particular by detecting impedance, resonancefrequency and/or induced voltage for detecting the strength of magneticcoupling, and/or by detecting if the intensity of data received by thedata transmission unit from a data transmission unit of the other deviceexceeds an intensity threshold, in particular by detecting signalintensity and/or antenna impedance of an antenna of the datatransmission unit for detecting the intensity of received data. 4.(canceled)
 5. Device as claimed in claim 1, wherein the datatransmission unit is configured to transmit the time stamp and/or adetermined relative difference between the clock signal used by thedevice and the clock signal of the other device to the other device forstorage in a master device of the system.
 6. Device as claimed in claim1, wherein the other device comprises a battery and wherein the highfrequency power signal used for transmitting power from the battery tothe device is used for determining and/or resetting the relative timedifference.
 7. Device as claimed in claim 6, further comprising abattery, wherein the control unit is configured to switch off thebattery or generate a control signal for transmission to the otherdevice for switching off the battery of the other device.
 8. Device asclaimed in claim 1, wherein the data transmission unit is configured toreceive a master clock signal from the other device or to transmit amaster clock signal to the other device.
 9. Device as claimed in claim1, further comprising a galvanic connection unit for galvanic couplingof the device to a third device having a counterpart galvanic connectionunit and for receiving a master clock signal from the third device forcalibrating the clock signal used by the device.
 10. Device as claimedin claim 1, further comprising a patient side connection unit forconnecting the device to one or more sensors to receive one or morephysiologic sensor signals, wherein the device is configured tocalibrate the clock signal used by the device based on a periodicity ofa received physiologic signal.
 11. Device as claimed in claim 1, furthercomprising a clock unit for generating the clock signal used by thedevice.
 12. Device as claimed in claim 1, further comprising a counterfor counting the number of pulses of the high frequency power signal,wherein the counted number is used for calibrating the clock signal usedby the device.
 13. Device as claimed in claim 12, wherein the counter isconfigured to reset to zero when the device is coupled to or decoupledfrom another device or when the inductive coupling is interrupted orwhen an external synchronization event is detected.
 14. Device asclaimed in claim 1, wherein the control unit is configured to decide ifa received or generated high frequency power signal is transmitted tothe other device or if a new high frequency power signal with differentfrequency and/or phase is regenerated.
 15. Device as claimed in claim 1,wherein said data transmission unit is configured for transmitting databy use of RF transmission, optical transmission, capacitive coupling ornear field communication.